Shift register loop

Thread Starter

GopherT

Joined Nov 23, 2012
7,983
I have not worked with shift registers in a while and when I did, it was fairly straightforward in to out. Now I have a question for a chaser project, is it possible to put two or more 'serial in/parallel out' shift registers together head-tail in a loop to pass the bits in a circle?

I am sure it can be done with a buffer flip-flop bit at the end of a head/tail series of shift registers (e.g. 'carry bit' for a rrf/rlf command) but can it be done only as a loop?
 

kubeek

Joined Sep 20, 2005
5,599
Yes you can, but you will need some glue logic to let you feed the pattern inside in the first place and then switch to circulation.
 

AnalogKid

Joined Aug 1, 2013
8,103
An alternative to kubeek's suggestion is a more complex shift register part that can be parallel loaded with the pattern. This is sometimes called a universal shift register because it is parallel in and out and serial in and out. 74195.

ak
 

Thread Starter

GopherT

Joined Nov 23, 2012
7,983
Yes you can, but you will need some glue logic to let you feed the pattern inside in the first place and then switch to circulation.
Yes, I already have the glue logic with a feed-in switch, a toggle for the logic level and a push button clock to feed in the first pattern. Then I'll flip the feed-in switch back to form the loop, start the real clock and away I'll go.
Thanks! Just wanted to make sure I wasn't missing out on something if they were cascading like dominos on each clock tick or if they all happen in unison. Cheers.
 

cmartinez

Joined Jan 17, 2007
6,462
Yes, I already have the glue logic with a feed-in switch, a toggle for the logic level and a push button clock to feed in the first pattern. Then I'll flip the feed-in switch back to form the loop, start the real clock and away I'll go.
Thanks! Just wanted to make sure I wasn't missing out on something if they were cascading like dominos on each clock tick or if they all happen in unison. Cheers.
Gopher, do you have a digital logic simulator? If you don't, then I suggest you take a look at digital works. It comes with some predefined logic chips and all.
 

Thread Starter

GopherT

Joined Nov 23, 2012
7,983
Gopher, do you have a digital logic simulator? If you don't, then I suggest you take a look at digital works. It comes with some predefined logic chips and all.
Thanks, I already have one but it did not include a shift register for some reason. Also, some little things do not simulate reality very well.
 
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